The invention relates to a clutch assembly with a friction clutch comprising a pressure plate which is non-rotatably connectable with a counterpressure plate for limited axial movement with respect thereto, at least one biasing spring being provided to urge the pressure plate toward a clutch disc which can be clamped between the pressure plate and the counterpressure plate and there being further provided an adjusting device to compensate at least for the wear upon the friction linings of the clutch disc to effect a substantially unchanged application of force by the biasing spring to the pressure plate, the friction clutch further comprising actuating means for engaging and disengaging the clutch and the actuating means being operable by a disengaging member which is shiftable axially by a disengaging means, e.g., a disengaging fork which is pivotably mounted on a transmission case.
A clutch assembly which is constructed and which is operable in the aforedescribed manner is known, for example, from the published French patent application No. 2 582 363. The actuating means of such clutch assemblies can be acted upon by disengaging systems or by disengaging means and a disengaging member in a manner as disclosed, for example, in U.S. Pat. No. 4,368,810, in U.S. Pat. No. 4,326,617, in the published German patent application No. 27 52 904 and in the published German patent application No. 27 01 999.
Clutch assemblies or friction clutches utilizing an integrated adjusting device which compensates at least for the wear upon the friction linings of the clutch disc exhibit the drawback that, especially when employing so-called mechanical disengaging systems wherein the movements of the clutch pedal are transmitted to the actuating means of the friction clutch by way of a linkage and/or a Bowden wire with the interposition of at least one disengaging bearing, due to tolerances within the entire kinematic train one cannot ensure that those portions of the disengaging member which act upon the actuating means invariably assume the same axial position relative to those portions of the actuating means which are to be acted upon. This can result in relatively large departures of the disengaging path of the friction clutch or of the extent of actuating movement which is being imparted to the actuating means. At the very least, such departure can adversely influence the operation of the adjusting device to such an extent that, under certain extreme circumstances, the adjusting device is no longer capable of carrying out its adjusting function. Furthermore, it can happen that, under certain circumstances when the actuating means covers an excessive distance resulting in undesired adjustment, the friction clutch is no longer capable of being properly disengaged or the initial stressing and the position of the biasing spring are altered to such extent that the force which is actually supplied by the biasing spring does not suffice to guarantee an acceptable transmission of torque.